.page {
  font-size: 20px;
  width: 600px;
  height: 400px;
  color: #333;
}
.container {
  border: 1px dotted sandybrown;
  display: flex;
  height: 100%;
}
.nav {
  display: flex;
  flex-direction: column;
  width: 130px;
  border-right: 1px solid silver;
  box-sizing: border-box;
}

.content {
  padding: 15px;
  flex: auto;
}
